| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | James Coleman <jtc331(at)gmail(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Shaun Thomas <shaun(dot)thomas(at)2ndquadrant(dot)com>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andreas Karlsson <andreas(at)proxel(dot)se> |
| Subject: | Re: [PATCH] Incremental sort (was: PoC: Partial sort) |
| Date: | 2020-03-31 17:04:28 |
| Message-ID: | 346.1585674268@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
James Coleman <jtc331(at)gmail(dot)com> writes:
> + * TuplesortMethod is used in a bitmask in Increment Sort's shared memory
> + * instrumentation so needs to have each value be a separate bit.
>> I don't quite understand why you skipped "1". (Also, is the use of zero
>> a wise choice?)
> The assignment of 0 was already there, and there wasn't a comment to
> indicate why. That ends up meaning we wouldn't display "still in
> progress" as a type here, which is maybe desirable, but I'm honestly
> not sure why it was that way originally. I'm curious if you have any
> thoughts on it.
As things stood, the "= 0" was a no-op, since the first enum value
would've been that anyway. But if you're converting this set of symbols
to bits that can be OR'd together, it seems pretty strange to use zero,
because that can't be distinguished from "absence of any entry".
Perhaps the semantics are such that that's actually sensible, but it's
far from a straightforward remapping of the old enum.
regards, tom lane
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